Formula to determine thrust using area, torque, pitch, etc? 1

[carpevis]

I'm a computer geek with an idea, but I'm a bit lost as to implementation and need the formulas to work with.

I'm trying to design a variable-pitch dual blade VTOL. I can 'do the math' if I know what the input for the problem is. The way I see it, I have to design the blades based on the engine and adjust the pitch from zero (no thrust) to x degrees (maximum thrust) at y RPM and z torque (or efficiency), but I have no idea what the formula is for diameter, width, speed, area, torque, etc... I expect the blades to be straight, as opposed to curved, recurved or anything like that - the math for that is way too hairy. This is a straight thrust vector problem, applying the thrust straight down and I'm not planning on using rotation of pitch for forward propulsion as with a helicopter. It's not something I studied in engineering dynamics.

I have a gross vehicle weight in mind, but can adjust it as needed depending on materials used, engine needed, and a few other items. But I need to do the math before I start the design so I know what kind of specifications for the powerplant and rotors I'll need for various weights in the design. Aerodynamic flow is actually not much of a consideration. It ain't gonna be a fast craft (about 100-150 MPH tops)

Oh, and does anyone know the thrust to weight ratio for a straight ascending line at, say, 250 and 500 feet per minute may be? I don't expect the crafct to go higher than, say 10,000 feet, and I can deal with air density changes once I know where they go in the formula.

Can anyone help? Thanks in advance!

 

[nlappos]

Its not cook-book, there are infinite variables, and even the experts get it almost right sometimes.
I would suggest Rotary Wing Aerodynamics, by Stepnewski and Keys, Dover publications, as a good basic discussion. But designing blades is one tough job, structurally and aerodynamically. It is a critical structure, in a whirling centrifugal field, with dynamic stability concerns, attachment structural concerns, structural modes, dynamic oscillations, and the like to make it complex. Plan to pack a lunch, it is an all-day job.

 

[AHPilot]

nlappos hit the nail on the head. In addition to the publication he suggests....Read pubs by Ray Prouty or try to contact him via email...I think he writes for Rotor&Wing again.